1. Make the Polenta: Preheat the oven to 400°. Bake the sweet potato for about 20 minutes, or until barely tender. Peel and cut the sweet potato into 1/2-inch dice. Raise the oven temperature to 500°. 2. Bring the chicken stock to a boil in a medium saucepan. Lightly oil a shallow 8-inch bowl. Wh...